The present invention relates to a slide member having a slide surface allowed to slide in contact with another member and treated for wear resistance and low friction resistance. In particular, the present invention relates to a slide surface structure of a wear resisting slide member useful for application to ordinary machine parts capable of relative sliding contact with each other, a slide bearing to be used in a vacuum, the inner and outer race surfaces of a ball-and-roller bearing, the thrust receive portion of a groove bearing, or the sliding contact portion of an artificial joint and the like.
As a pair of slide members arranged to slide in contact with each other and including a slide surface which is treated for wear resistance, for example, there are known metal slide members which are disclosed in Unexamined Japanese Patent Publication No. Sho. 60-135564. According to this publication, a wear resisting hard material and a solid lubricant are divided into blocks and are then evaporated spatteringly onto the slide surface of at least one of the two metal member arranged to slide in contact with each other to thereby provide an evaporated surface having a mottled pattern or a dimple pattern (which will be hereinafter referred to as a mottled pattern) formed by the hard material evaporated portions and solid lubricant material evaporated portions. According to this structure, loads are received by the hard material portions arranged to come into sliding contact with the mating metal member, and the solid lubricant disposed so as to surround the hard materials is dug up by sliding in contact with the mating metal member and is then supplied to the hard material portions as a lubricant, so that the wear resistance of the slide metal members can be increased and at the same time the friction thereof can be reduced.
In another conventional example, there is known a wear resisting slide member in which a projected and recessed surface is formed on the surface of the mother member of the slide member, a solid lubricant film is formed directly on the projected and recessed surface or a hard material layer is formed on the projected and recessed surface so far as the projected and recessed shape can be maintained and, after then, a solid lubricant film is formed in the recessed portions of the upper-most layer, which prevents the solid lubricant film from being peeled off due to shearing stresses produced during the sliding movement and also makes it possible to perform its wear resisting property and a sufficient lubricating property (see Unexamined Japanese Patent Publication No. Hei. 2-76925).
In both of the conventional metal slide member and wear resisting slide member, while the slide member is in sliding movement, the lubricant is supplied from the solid lubricating surface thereof to the wear resisting hard material surrounding the solid lubricating surface or to the projected portions of the sliding surface of the mother member thereof, so that there can be obtained a high lubricating property; and, since the loads are received by the wear resisting hard material or by the projected portions of the projected and recessed pattern, the load capacity as well as dimensional accuracy of the slide member can be improved. However, the above-mentioned Unexamined Japanese Patent Publication No. Sho. 60-135564 teaches only that an area ratio between the two materials of the mottled pattern of the slide surface of the slide member including the hard material portion and solid lubricant material portion is determined experimentally according to the using conditions of the respective members, and the area ratio is not specified concretely. Also, in the teachings of the Unexamined Japanese Patent Publication No. Hei. 2-76925, although the diameters of the respective tubular or cylindrical recessed or projected portions are shown, the number of them as well as the distribution of them are not shown, that is, the area ratio of the recessed or projected portions with respect to the whole slide surface are not illustrated.
In the slide member with the projected and recessed pattern formed in the above-mentioned manner, since a load is received by the projected portions and the lubricant is supplied from the recessed portions, if the area of the projected portions is small, then the load resisting property of the slide member is lowered and, on the other hand, if the area of the whole projected portions is great or the area of the recessed portions is small, then the capacity of supply of the lubricant is lowered. And, if the depth of the recessed portion is great, then the lubricant is difficult to flow out from the recessed portions and, if the recessed portion is too shallow in depth, then the lubricant cannot be held effectively. Therefore, in order to perform the low friction resistance and wear resistance of the slide member to the full, it is necessary to set the area ratio between the recessed and projected portions of the projected and recessed pattern and the depth of the recessed portion for the optimum values respectively.